An observational analysis of the variability of the sea surface heat flux in the Kuroshio Extension

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An observational analysis of the variability of
the sea surface heat flux in the Kuroshio
Extension region

• Masanori Konda
• (Kyoto University / JAMSTEC IORGC)
• Hiroshi Ichikawa, Hiroyuki Tomita, Akira Nagano
• (JAMSTEC IORGC)
• Meghan F. Cronin
• (NOAA PMEL)

US CLIVAR WBC Workshop 15/Jan. 2009, Phoenix
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outline

• JKEO status
• Surface turbulent heat flux pattern in the KE
  observed by KEO and JKEO (2007-2008 analysis)
• Difference between the KEO and JKEO(one
  dimensional air-mass transformation)

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JKEO (JAMSTEC Kuroshio Extension Observatory)

• the north side of the Kuroshio Extension (KEO in
  the other side)
• To measure the ocean meteorology, the radiation,
  water temperature and salinity
• The in situ observation for the validation of
  satellite-derived variables.

JKEO 38.0 N 146.5 E
JKEO1 -gt K-TRITON
KEO 32.4 N 144.6 E
OCEAN SITES data format as well as ASCII real
time and delayed data Visit http//www.jamstec.go.
jp/iorgc/ocorp/ktsfg/data/jkeo/index.html And
http//www.pmel.noaa.gov/keo/
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Sensor arrangements of JKEO1 and K-TRITON (JKEO2)
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The surface meteorology at JKEO1 and KEO
18 Feb-13 Mar 2007

• Wind is missed from Mar 13 to May 10.
• Meteorological sensors (except for AT) are from
  Sep. 9 to Oct. 4.
• All of meteorological sensors stop on Jan. 26
  2008.
• Mar 2009 JKEO1 is recovered and replaced by
  K-TRITON (JKEO2).
• JKEO2 stopped on 28 May because of the vandalism
  (recovered on 5 Sep).
• JKEO3 is deployed on 12 Nov.
• Delayed mode data of JKEO1 is almost processed.
• Real time mode data of JKEO2 and 3 data is under
  formatting.

SST
4 Oct- 25 Jan. 2008
Ta
RH()
U
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Temperature profile at JKEO (and KEO)

• Sensor failed at
• 15m on Feb.24, 20m on May
  28, 10m on Jun. 8.

The KE front
Difference between the north and the south of the
KE front with temporally high resolution
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Satellite-derived and NNR latent heat fluxes
2000 January
Consistent or not ?
JKEO
JKEO
KEO
KEO
NNR1
satellite
Generally large around the KE frontal region
2001 January
JKEO
JKEO
KEO
KEO
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JKEO - KEO surface heat flux variation
SST
LHF
Ta
SHF
DPT
Individual parameters have a strong contrast
across the KE front, whereas the resultant heat
flux does not has it.
Wind
Feb. 19 (Deployment of JKEO) Mar. 22 2007
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Latent heat flux components
Latent heat flux
Suggesting a quick one dimensional adjustment of
the atmosphere?
Term i bias
Small north-south difference
Term ii ?q anomaly
Advection of the atmospheric column ?
Mar.15
Mar.1
Feb.24
Term iii U anomaly
Wind direction
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Spatial anomaly analysis
Spatial difference between JKEO and KEO
(i) spatial difference (ii) ?q spatial
anomaly (iii) U spatial anomaly (iv) ignored
(ii) and (iii) are almost balanced during the
strong north wind period. The wind is
stronger in the north, while the air-sea humidity
difference is largerin the south because of
Clausius-Clapeyron relationship, suggesting the
air-mass transfer
LHF
SHF
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Spatial anomaly analysis
Spatial difference between JKEO and KEO
(i) spatial difference (ii) ?T spatial
anomaly (iii) U spatial anomaly (iv) ignored
(ii) And (iii) are not balanced. The wind is
stronger in the north, and the air-sea
temperature difference is also larger in the
north. The sensible heat fluxes change
synchronously, but that in the north is larger.
LHF
SHF
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Satellite snapshot complements the spatial pattern
Feb.26
Latent heat flux
Term i bias
KE front
Term ii mean U, ?q anomaly
Latent heat flux
Term iii mean ?q, ,U anomaly

• JKEO behind the strong low
• ? Strong wind/small ?q
• KEO behind the strong low
• Warm condition / large ?q
• Increase of the latent heat flux at the KE front
  under the same stream line of the wind

L
Wind direction
Bond and Cronin (2008)
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Latent heat flux components 2007-2008
Latent heat flux
Low pressure crossing
Term i bias
Small north-south difference
Term ii ?q anomaly
Jan. 25
Jan. 13
Dec 31
Term iii U anomaly
Wind direction
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The KE Region Anomalous heat loss and gain
associated with ????? (Bond and Cronin 2008)

• Differences between the anomalously heat loss and
  gain in the cold season is extracted from the
  NNR data set.
• KEO is located on the flank of the region with
  large atmospheric anomaly.
• The largest SST difference is centered on the
  JKEO region.
• The difference between KEO and JKEO is quite
  large.

L
H
H
SLPA during anomalous heat loss
SLPA during anomalous heat gain
Difference in TA(850hPa) between anomalous heat
loss and gain
Difference in SST between anomalousheat loss
and gain
Fig. 8 in Bond and Cronin (2008)
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Latent heat flux components in October 2007
Mixed layer is not evident -gt SST is easily to
decrease
Latent heat flux
Contribution of the mean field is almost the same
Mixed layer is formed
Term i bias
Variability of the sea-air (temperature and
humidity) difference changes across the KE front.
Spatial anomaly
Term ii ?q anomaly
Synoptic scale disturbance might be weak
Term iii u anomaly
Wind direction
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summary

• The north-south contrast of the air-sea coupling
  processes across the KE
• Latent heat fluxes under the strong north wind
  are almost same, as the result of the quick one
  dimensional adjustment of the atmosphere (The
  KEO-JKEO gap may be too large to resolve it.)
• Frequency of the typical wind pattern possibly
  may determine the anomalous flux distribution
  rather than the long-lasting bias.
• The role of the SST front changes seasonally.
• The winter time cross-frontal wind effect can
  change the ocean mixed layer rapidly.
• Year-to-year variation needs longer observation.
• On site measurements satellite measurements
  numerical model products can complement each
  other.
• The scenario suggested here should be checked
  with satellite data and the numerical model
  result.

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NCEP-Reanalysis 1 latent heat flux
February-March 2007
January 2008
JKEO 168.3 (121.4) W/m2 KEO 237.0 (101.9) W/m2
JKEO 177.5 (91.1) W/m2 KEO 215.5 (93.6) W/m2